Support processing round dependencies

[Leland-Takamine]

Today, Motif's processor assumes that all types are available in the current annotation processing round. This may not be the case if another processor or processing round is expected to generate a provided dependency, for instance. To support processing rounds dependencies, Motif will need to defer processing if it encounters an error type.

[Leland-Takamine]

We're using BasicAnnotationProcessor now so this should be fine from Motif's perspective. However, there are limitations as outlined here: google/auto#660